1. Field of the Invention
The present invention is related to telecommunications systems and more particularly, to Session Initiation Protocol (SIP) based telecommunications networks.
2. Background Description
Commercial telecommunications platforms have allowed service providers to deliver Internet Protocol (IP) based telecommunications services. Typical such IP telecommunications services feature common channel telecommunications packet switching capabilities, such as Signaling System Number 7 (SS7) signaling capabilities. These capabilities allow for legacy feature support and, further, interconnection with Public Switched Telephone Networks (PSTN). Digital communications such as Voice over IP (VoIP), for example, normally use Session Initiation Protocol (SIP) for establishing and clearing of connections-between network stations at SIP endpoints.
In a typical such enterprise communications environment/network a keyset may have multiple line appearances at a SIP endpoint, e.g., up to 30 appearances. Each appearance is a communications resource in that network and is assigned a unique Uniform Resource Indicator (URI). Also, a single line with an assigned associated Directory Number (DN) may be shared by multiple (e.g., up to 40) keysets. That line is a line appearance on each keyset.
Under current SIP standards every line appearance is registered with the network. Each registration is continually maintained. Both the initial registration and maintaining registrations consumes time and resources. Since all primary, secondary and phantom lines on any SIP endpoint must register and all shared lines must register, each of these registrations consume SIP endpoint resources. This limits the number of line appearances that can be assigned to the network and to each SIP endpoint.
Typically a call is placed to each incoming call by providing an “INVITE” message to every line appearance associated with a respective dialed destination, i.e., Directory Number/associated line. The typical INVITE message establishes early media, which eliminates any speech clipping issues that might otherwise subsequently arise when the destination answers the pending incoming call. A typical INVITE message is relatively large and consumes additional SIP endpoint resources and processing. This use of resources also reduces the amount of traffic that the network can handle. Consequently, the processing and resource consumption from both registering all line appearances and, then, widely distributing each INVITE message limits the number of line appearances for any given network.
Thus, there is a need for minimizing the number of registered appearances on a SIP based communications network and, further for reducing the cumulative resources consumed by INVITE messages.